1. Field of the Invention
The present invention relates to a motion picture camera which includes a built-in color conversion filter capable of being inserted into and removed from the photographic optical path so as to enable the change over of the photographic modes between the daylight photography and the tungsten light photography so that the tungsten type film and the daylight film can be used selectively.
2. Description of the Prior Art
So far, the so called super 8 system of the 8 mm motion picture camera is so designed that, in principle, the tungsten type film is used, whereby a color conversion filter (hereinafter called A type filter) for adapting the film to the daylight photography is built in. This is done so that, in case of the tungsten light photography, the filter is retired out of the photographic optical path manually or in functional engagement with the mounting of the tungsten light source on the motion picture camera so as to change over the photographic mode has been proposed, for example, by U.S. Pat. No. 3,208,363 (corresponding to DAS 1,204,520) and DAS 1,472,730.
The above mentioned system is in principle intended for the tungsten type film while the daylight film can also be used. In order to use the daylight film, the above mentioned A type filter has to be taken out of the photographic optical path. For this purpose, for example, a notch is provided on one part of the outer wall of the film cartridge containing a tungsten type film to indicate that the film contained in the film cartridge is of the tungsten type while no such notch is provided on the film cartridge containing the daylight film. Accordingly by making use of this difference, the selection as to whether the above mentioned filter is to be left in the photographic optical path or taken out of the optical path is automatically made at the time of loading the film cartridge into the camera.
Further in accordance with this system, another notch is provided on the film cartridge to automaticaly adjust the exposure of the camera in accordance with the sensitivity of the loaded film. Thus the position of the notch is so chosen that for example that of a tungsten type film (ASA40) coincides with that of a daylighr film (ASA25) in such a manner that the difference between the sensitivities coincides with the exposure compensation factor of the above mentioned A type filter.
Therefore, in the present system, in order to change over the daylight photographic mode with tungsten type film into the tungsten light photographic mode with tungsten type film, the A type filter is taken out of the photographic optical path whereby the substantial sensitivity of the film is increased so that it becomes necessary to compensate the sensitivity of the exposure meter device correspondingly. This is carried out for example in such a manner that the ND filter (neutral density filter) provided for insertion into or removal from the incident light optical path of the light sensing element in the exposure measuring circuit is retired out of the incident optical path in functional engagement with the retirement of the above mentioned A type filter or the value of the resistance in the exposure measuring circuit is varied in functional engagement of the above mentioned A type filter.
This compensation of the sensitivity of the exposure meter device is necessary only in case of changing over the daylight photographic mode with tungsten type film into the tungsten light photographic mode with tungsten type film and not necessary at all in the case of photographic mode with daylight film. However, in the case of the camera so designed that the change over operation of the photographic modes (including the compensation operation of the sensitivity of the exposure meter device) is manually carried out, such misoperation often takes place as the unnecessary compensation of the sensitivity of the exposure meter device is carried out even in the case of the tungsten light photographic mode with daylight film so that pictures with remarkably inproper exposure are often taken.